Ž .
Animal Reproduction Science 60–61 2000 629–642 www.elsevier.comrlocateranireprosci
Epidemiologic concerns relative to in vivo and in vitro production of livestock embryos
D.A. Stringfellow , M.D. Givens
Department of Pathobiology, College of Veterinary Medicine, 166 Greene Hall, Auburn UniÕersity, Auburn, AL 36849-5519, USA
Abstract
Evidence indicates low potential for transmission of pathogens with in vivo-derived embryos of cattle when appropriate precautions are taken. In apparent contrast, results of research with in
vivo-derived embryos of small ruminants and swine and with in vitro-derived embryos of cattle suggest a greater tendency for their association with pathogens after artificial exposure. However,
regardless of donor species, investigations involving collection of embryos from artificially or naturally infected animals and assessment of health of recipients and offspring after transfer of
these embryos have indicated low potential for transmitting disease.
In this paper, results of embryo–pathogen research are summarized, emphasizing potential for spread of pathogens under natural circumstances. Also, safe embryo handling practices and their
application to multiple species are discussed. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Livestock embryo; Embryo–pathogen interaction; Embryo washing
1. Introduction
Methods used to produce specific-pathogen-free embryos from livestock have in- cluded testing of donor animals before and after embryo collection, treatment of
embryos after collection, or a combination of donor testing and embryo treatment Ž
. Givens and Stringfellow, 1999 . Donor testing is a conservative approach that provides
Ž considerable assurance that donors are free of specific infectious agents Stringfellow,
. 1985 . However, this approach is expensive and time consuming compared to embryo
Ž .
treatment. Embryo treatments i.e., washing with or without trypsin that are recom-
Corresponding author: Tel: q1-334-844-2667; fax: q1-334-844-4955. Ž
. E-mail address: strindavetmed.auburn.edu D.A. Stringfellow .
0378-4320r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž
. PII: S 0 3 7 8 - 4 3 2 0 0 0 0 0 1 0 4 - 4
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mended by the International Embryo Transfer Society Stringfellow, 1998 are simple, relatively inexpensive procedures that can be applied routinely in embryo production.
Furthermore, embryo washing for health certification of in vivo-derived bovine embryos was validated in numerous studies that have been summarized in detail elsewhere
Ž
. Singh, 1987; Stringfellow et al., 1991; Anonymous, 1998a . In comparison, research on
the epidemiology of in vivo-derived embryo production in small ruminants and swine and in vitro-derived embryo production in cattle has been less complete, and results
indicate a greater tendency for association of pathogens with these embryos after Ž
. artificial exposure Anonymous, 1998a; Guerin et al., 1997 . In this paper, results of
embryo–pathogen research with in vivo-derived embryos of cattle, small ruminants and swine and with in vitro-derived embryos of cattle are summarized and compared,
emphasizing potential for pathogen transmission under natural circumstances. In addi- tion, safe embryo handling practices and their application to multiple species and
embryo production circumstances are discussed.
2. Bovine embryo–pathogen research
